Facebook is giving advertisers visibility into which publishers their ads might appear on as part of wider push for brand safety on the platform.

According to an announcement being made Sept. 10, advertisers can now see where their ads might appear on in-stream videos, including those in Watch and Instant Articles, before, during or after a campaign, so they can block specific publishers or content categories from those placements. They can also review and update from a list that Facebook regularly adds to.

Those lists, however, only let advertisers block publishers they’re aware of, which means their ads could still appear against unsuitable content from publishers they don’t know.

“If you block a publisher post-impression, the possible damage has been already done and all you do is limit the reach,” said Christian Dankl, chairman at contextual targeting platform Precise.TV. “To ensure brand relevance and safety, Facebook should offer the ability to create a publisher whitelist and give full control in the hands of advertisers.”

Facebook could let advertisers use whitelists to give them full control over where their ads appear, but then that would limit Facebook’s ability to monetize its video. Instead, the social network is trying to monetize the video it does have across more publishers while it amasses more video inventory. Formats like pre-roll and mid-roll are critical for Facebook’s play for brand dollars, whereas direct response-focused brands in the news feed may not care as much. Facebook doesn’t have enough video in-stream inventory to profit from whitelist targeting, according to four media executives interviewed for this article.

“The market expects Facebook to have more control of the environment where brands appear, without compromising the potential reach and available inventory,” said Sergio Fernandez, digital performance director at MullenLowe Mediahub. “This last point is also one of the adjacent issues brands need to evaluate when they go for a very restrictive safety strategy. In addition to this, an accurate label of publishers would make it easier for advertisers and agencies to select the right placements.”

Facebook has traditionally made most of its revenue from display ads in the news feed, not in-stream, so the issues of brand safety were largely contained. The decision earlier this month to make it easier for more creators to monetize their videos in Watch could create more ad inventory, which brings with it greater risk to brand safety.

The social network has stepped up efforts in recent months to guarantee a safer environment for advertisers. Plans are already underway to allow advertisers to use third-party companies to target in-stream ads on to users based on the content of the video they’re watching on Facebook. Despite those efforts, some brands are either not using the updates Facebook has already made or are not aware of them, said Fernandez.

Another executive, who spoke to Digiday, said they expect that to change once Facebook starts pitching Watch to media agencies. “As it stands, Watch is pretty safe because it’s been such a premium and curated environment,” said the executive, speaking on condition of anonymity for fear of jeopardizing their relationship with Facebook. “That’s changing now that people realize the threshold to monetizing is lower. Facebook are trying to head brand safety off at the pass.”